Dipeptidyl peptidase IV is a membrane bound non-classical serine aminopeptidase which is located in a variety of tissues including, but not limited to, intestine, liver, lung, and kidney. This enzyme is also located on circulating T-lymphocytes wherein it is referred to as CD-26. Dipeptidyl peptidase IV is responsible for the metabolic cleavage of the endogenous peptides GLP-1(7-36) and glucagons in vivo and has demonstrated proteolytic activity against other peptides such as GHRH, NPY, GLP-2 and VIP in vitro.
GLP-1(7-36) is a 29 amino acid peptide derived from post-translational processing of proglucagon in the small intestine. This peptide has multiple actions in vivo. For example, GLP-1(7-36) stimulates insulin secretion and inhibits glucagon secretion. This peptide promotes satiety and slows gastric emptying. Exogenous administration of GLP-1(7-36) via continuous infusion has been shown to be efficacious in diabetic patients. However, the exogenous peptide is degraded too rapidly for continual therapeutic use.
Inhibitors of dipeptidyl peptidase IV have been developed to potentiate endogenous levels of GLP-1(7,36). U.S. Pat. No. 6,395,767 to Hamann et al. discloses cyclopropyl-fused pyrrolidine-based inhibitors of dipeptidyl peptidase IV. Methods for chemically synthesizing these inhibitors are disclosed in U.S. Pat. No. 6,395,767 as well as in the literature. For example, see Sagnard et al. Tet-Lett. 1995 36:3148-3152; Tverezovsky et al. Tetrahedron 1997 53:14773-14792; and Hanessian et al. Bioorg. Med. Chem. Lett. 1998 8:2123-2128. A preferred inhibitor disclosed in U.S. Pat. No. 6,395,767 is (1S,3S,5S)-2-[(2S)-2-amino-2-(3-hydroxytricyclo[3.3.1.13,7]dec-1-yl)-1-oxoethyl]-2-azabicyclo[3.1.0]hexane-3-carbonitrile, as depicted in Formula M′.
and the corresponding monohydrate of (1S,3S,5S)-2-[(2S)-2-amino-2-(3-hydroxy-tricyclo[3.3.1.13,7]dec-1-yl)-1-oxoethyl]-2-azabicyclo-[3.1.0]hexane-3-carbonitrile (M″)
Methods adapted for preparing intermediates used in the production of this dipeptidyl peptidase IV inhibitor are disclosed in EP 0 808 824 A2. Also see, Imashiro and Kuroda Tetrahedron Letters 2001 42:1313-1315, Reetz et al. Chem. Int. Ed. Engl. 1979 18:72, Reetz and Heimbach Chem. Ber. 1983 116:3702-3707, Reetz et al. Chem. Ber. 1983 116:3708-3724.
The present invention provides new production methods and compounds for use in the production of cyclopropyl-fused pyrrolidine-based inhibitors of dipeptidyl peptidase IV.
U.S. Pat. No. 6,395,767 to Hamann et al. describes procedures for the synthesis of (αS)-α-[[(1,1-dimethylethoxy)carbonyl]-amino]-3-hydroxytricyclo[3.3.1.13,7]decane-1-acetic acid, an intermediate for use in preparing the free base M′ or salt thereof, which involves an eight-step synthesis from adamantane carboxylic acid.
U.S. application Ser. No. 10/716,012 filed Nov. 18, 2003 discloses a method for preparing (αS)-α-[[(1,1-dimethylethoxy)carbonyl]-amino]-3-hydroxytricyclo[3.3.1.13,7]decane-1-acetic acid which utilizes 3-hydroxy-α-oxotricyclo[3.3.1.13,7]-decane-1-acetic acid as a starting material and wherein an enzymatic reductive amination is used to prepare and isolate (αS)-α-amino-3-hydroxytricyclo[3.3.1.13,7]decane-1-acetic acid which is converted to the desired product in a separate step.
The enzymatic reductive amination step involves use of various forms of the enzyme phenylalanine dehydrogenase (PDH) in combination with the enzyme formate dehydrogenase enzyme (FDH) in the presence of ammonium formate, DTT and NAD using ammonium hydroxide for pH adjustment. Where excess ammonium ions are present, it may be necessary to remove ammonia before further downstream processing to avoid possible interference with the introduction of a BOC group.
The cells from which the PDH and/or FDH enzymes are produced are isolated from fermentation broth, stored until ready for use. Before using, the cells are microfluidized to release enzyme from the cells together with the cell debris which must be removed before the enzymes are ready for use in reductive amination.